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    <title>Document</title>
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        * {
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            padding: 0;
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        /* .screen {
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            height: 100%;
        } */
        .box {
            width: 100%;
            height: 100%;
            justify-content: center;
            display: flex;
            align-items: center;
            

        }

        /* .bigbox {
            width: 100%;
            position: relative;
        } */
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<body>
    <div class="box">slie1</div>
    <div class="box">slie2</div>
    <div class="box">slie3</div>
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